An unseasonal heat wave that hit the nation last week would not have happened without human-induced climate change, a group of Japanese scientists said Thursday.

The World Attribution Center (WAC), comprised of independent climate researchers, analyzed the impact of global warming on the nation’s weather between June 16 and June 18. The average temperature 1,500 meters above sea level during this period was 17.2 degrees Celsius, the highest since 1950. Also, the total number of locations where the highest temperature reached 35 degrees C or higher from May 1 through mid-June topped 200, the highest on record.

The heat observed during this period was extremely rare, especially since much of Japan is still in the rainy season, with scorching temperatures coming just a week after the rainy season began in the Kanto-Koshin region, which includes Tokyo.